Physics

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    IV characteristics of ITO/Cu2O/ metal junctions
    (1996) Perera, L.D.R.D.; Siripala, W.; Kalingamudali, S.R.D.; Jayanetti, J.K.D.S.; de Silva, K.T.L.
    Cuprous oxide is an inexpensive and non-toxic semiconductor material having the potential for use in low-cost photovoltaic devices. Electrodeposition is a low-cost method t0 produce thin Cu2O films and electrodeposited CU2O has been reported to be n-type, In order to investigate the possibility of using electrodeposited Cu2O in solar cells, Cu2O/metal junctions were studied using their I-V characteristics. Thin films of Cu20 were electrodeposited on Indium tin oxide (ITO) coated glass substrate using an aqueous solution of cupric acetate. Electrodeposition was carried out under potentiostatic condition of -250 mV vs SCE at 55"C for a period of 1 h. These Cu20 samples were used to make junctions with Al, Hg,Cu, Ag and Au. The I-V plots of these junctions were obtained in dark and when illuminated. The I-V characteristics of the Cu2O/Hg junction show good rectifying properties.The plots for the junction in dark and under illumination indicate that the electrodeposited Cu2O behaves as an n-type semiconductor. The I-V profile fits into the standard diode equation with I0 = 2.8 x 10 -10 A, ideality factor n=0.48 and series resistance Rs = 40U. Also, the Junction exhibits a contact potential of about 150 mV.
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    Photoelectrochemical Characterisation of ZnSe coated Copper Indium Sulphide Thin Film Electrodes
    (1999) Wijesundera, R.P.; Siripala, W.; Jayasuriya, K.D.; Kalingamudali, S.R.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.
    Capper Indium Sulphide thin films were prepared by sulphidation of Cu-In alloy on Ti substrate. Cu-In alloy was potentiostatically electrodeposited at ~1.4 V Vs SCE in an aqueous bath containing 5 mM CuCl2) 37.5m1 InCl3,1% (V/V) TEM and .75% (V/V) ammonia. Sulphidation was carried out in saturated H2S gas at 550�C for 30 min. XRD measurement reveals that the crystal structure of the films is CuInl1S17. ZnSe was deposited on CuInS electrode by electrodeposition in an aqueous bath of 0.1 M ZnS04 and 10 -5 M Se02 at -0.5 V Vs SCE for 90 min. XRD measurement reveals that the ZnSe films are amorphous. Ti/CulnS/ ZnSe thin film system in a PEC cell containing KI produces n-type photocondutivity. Dark and illuminated I-V measurement shows the existence of a main junction. However, some departure is also evident suggesting the possibility of existence of another junction. Spectral response of the Ti/CuInS/ZnSe system in a PEC cell shows the photoresponse of born n-CuInS/p-ZnSe and p-ZnSe/electrolyte interfaces. Normally, for shorter wavelength the spectral response is p-type while for the long wavelength it is n-type. The preliminary results of the study suggest the possibility of utilising electrodeposited n-CuInS in combination with electrodeposited p-ZnSe in developing a low-cost thin film solar cell.
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    Growth and Characterisation of CuInS2 Thin Films
    (1999) Wijesundera, R.P.; Siripala, W.; Jayasuriya, K.D.; Kalingamudali, S.R.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.; Samantilleke, A.P.; Dharmadasa, I.M.
    Copper Indium Disulphide thin films were grown by electrodeposition of Cu-ln alloy followed by sulphurisation in H2S gas. It was observed that the ionic concentration of Cu2+/ In3+ in the electrodepositing bath determines the composition of the materials formed after the sulphurisation. CuInS2 thin films having the chalcopyrite crystal structure can be produced using this technique and the films are n-type semiconductors.
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    Fabrication and Characterisation of CuinS2/ZnSe/Metal Structures for Solar Cell Applications
    (2000) Kalingamudali, S.R.D.; Wijesundera, R.P.; Gunatunga, N.P.; Siripala, W.; Jayasuriya, K.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.
    Thin film solar cell structure of Ti/CuInS2/ZnSe/Metal was fabricated using simple electrochemical and sulphurisation techniques. Copper lndium Disulphide (CuInS2 thin films were prepared by sulphurisation of Cu-In alloy on Ti substrates. Films were characterised usrng X-ray diffraction (XRD)1 scanning electron microscopy (SEM), spectral response and t-V measurements. XRD measurements snowed the characteristic peaks of CulnSz and SEM showed that the crystallites are of the size 1-3 J.1m. ZnSe thin fitms were deposited on Ti/CuInS2 using electrodeposition technique, TiCuInS2/ZnSe/Metal structures were characterised using C-V, I-V and spectral response measurements. Light and dark I-V measurements revealed the phctovoltaic activity of the structure while the C-V measurements confirmed the formatlon of the heterojunction. Spectral response showed that the photocarriers are generated by the absorption of light in the CuJnS2 tayer.